Intervertebral disc prosthesis and instruments for locating same

ABSTRACT

A collapsible plastic bladder-like prosthesis of the same external form as the nucleus pulposis of an intervertebral disc has a stem through which liquid and/or plastic is introduced to inflate the prosthesis to natural form. The top and bottom have stud-like protrusions which fit into sockets which have been forced through the bony end plates of the bodies of adjacent vertebrae anchoring the prosthesis against slippage. To install the prosthesis, the first step is to insert a transparent tube to the situs with a projecting pin fitting into an adjacent vertebrae to hold the distal end against slippage. A cystoscope may be inserted through the tube to check its location. The degenerated nucleus pulposis of the natural disc is removed in pieces by a forceps inserted through the tube and an incision in the disc wall. The tube provides controlled depth of penetration of this forceps into the disc and acts as a safety feature against injury to blood vessels, nerves and other structures adjacent to the disc. The socket members are inserted through the tube by a specially formed forceps and forced into the adjacent vertebrae. The collapsed prosthesis is then inserted through the stem, the studs pushed into the sockets. Pressure may be adjusted over a period of time; and when finally determined, the stem is severed.

United States Patent 1191 Froning 1 INTERVERTEBRAL DISC PROSTHESIS ANDINSTRUMENTS FOR LOCATING SAME [76] Inventor: Edward C. Froning, 215 NSan Mateo Dr., San Mateo, Calif. 94401 [22] Filed: Apr. 15, 1974 2 1]Appl. No.: 460,726

[52] U.S. Cl. 3/1; 128/92 C; 128/92 E; 128/303 R [51] Int. Cl A6 1/24;Afilb 17/00 [581 Field of Search 3/1. 36; 128/92 C. 92 CA. 128/92 R. 334R. 92 E. 92 EA, 92 G. 303 R,

Primary Examiner-Ronald L. Frinks Atmrney, Agent. or Firm-Julian Caplan[451 Apr. 8, 1975 57 ABSTRACT A collapsible plastic bladder-likeprosthesis of the same external form as the nucleus pulposis of anintervertebral disc has a stem through which liquid and/or plastic isintroduced to inflate the prosthesis to natural form. The top and bottomhave stud-like protrusions which fit into sockets which have been forcedthrough the bony end plates of the bodies of adjacent vertebraeanchoring the prosthesis against slippage. To install the prosthesis,the first step is to insert a transparent tube to the situs with aprojecting pin fitting into an adjacent vertebrae to hold the distal endagainst slippage. A cystoscope may be inserted through the tube to checkits location. The degenerated nucleus pulposis of the natural disc isremoved in pieces by a forceps inserted through the tube and an incisionin the disc wall. The tube provides controlled depth of penetration ofthis forceps into the disc and acts as a safety feature against injuryto blood vessels. nerves and other structures adjacent to the disc. Thesocket members are inserted through the tube by a specially formedforceps and forced into the adjacent vertebrac. The collapsed prosthesisis then inserted through the stem. the studs pushed into the sockets.Pressure may be adjusted over a period of time; and when finallydetermined. the stem is severed.

13 Claims, 9 Drawing Figures INTERVERTEBRAL DISC PROSTHESIS ANDINSTRUMENTS FOR LOCATING SAME This invention relates to a new andimproved intervertebral disc prosthesis and instruments for locating thesame in place.

A principal purpose of the present invention is to provide a prosthesicreplacement for a damaged intervertebral disc. The prosthesis resemblesin plan view the nucleus pulposis of the natural disc which it replaces.Since no spine fusion is employed bending of the spine in a naturalmanner is not inhibited.

In the lumbar area the entry to the disc is laterally, thereby reducingthe complexity and risk of intraspinal surgery traditionally employed.The danger of perforation of the nerve, dural sac, arteries and otherorgans is reduced. In cervical surgery, the approach is frontally andagain the complexity and risk of the surgery is greatly reduced byavoiding transgression of the spinal canal.

A further principal purpose of the invention is the provision of meansshielding the instruments which are used from the surrounding anatomyand thus damage to such anatomy, such as the cutting of nerves, iseliminated.

A still further purpose of the invention is the provision of anchoringmeans which prevent slippage of the prosthesis after applied.

A still further feature of the invention is the fact that the prosthesisis a hollow, flexible bladder-like member which is filled with a fluidand/or plastic under adjustable pressure. The pressure may be increasedor decreased while the prosthesis is in place over a period of time todetermine by trial and error the optimum pressure, and thereupon thestem of the prosthesis is removed. The optimum pressure is maintainedover an indefinite period of time by providing an inflating fluid orplastic having properties for holding fluid or water under pressurenormally occurring within the disc sufficient to avoid depletion of theinflating contents, a feature which would duplicate the feature of thenormal disc. The inflatable prosthesis and its inflating contents willconform to electrical conductive or insulating properties found in thenatural state.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

In the drawings:

FIG. 1 is a perspective view of the third and fourth lumbar vertebraesfrom the back and showing a tube and pin inserted.

FIG. 2 is a schematic sectional view showing tube and pin in place andalso showing use of a forceps to remove the nucleus of the disc.

FIG. 3 is similar to FIG. 2 showing insertion of sockets in the upperand lower surfaces of the adjacent vertebrae.

FIG. 4 is a view similar to FIG. 2 showing insertion of the collapsedprosthesis.

FIG. 5 shows inflation of the prosthesis and the studs thereof fittinginto the sockets.

FIG. 6 is a view similar to FIG. 1 showing the prosthesis in place.

FIG. 7 is an enlarged fragmentary view showing interfitting of stud andsocket.

FIG. 8 is a schematic vertical sectional view of cervical vertebrae,showing the prosthesis in place.

FIG. 9 is an enlarged section view taken substantially along line 9-9 ofFIG. 8.

A natural vertebral disc 12 comprises an outer annulus fibrosis l3 andan inner nucleus pulposis 14. The disc functions to permit flexiblearticulation of the adjacent vertebrae 11 and an internal resistance toflexion (or a bending torque) which lends intrinsic stability to thismultisegmented column. The nucleus is removed in accordance with themethod of the surgical treatment hereinafter described, preferably beingremoved by the method of chemonucleolysis an injection treatment with anenzyme such as chymopapain, a papaya derivative, which dissolves out thenucleus. It will be understood that the nucleus may be removed in othermanners.

The body 16 of vertebrae 11 has concave upper and lower surfaces 17 withraised marginal edges 18. A layer of cartilage 19 covers the surfaces17. Various processes 21 extend from body 16 and these shield the spinalcord 22 and provide attachment for muscles. Nerves 23 extend from cord22 in the interstices ofthe processes 21.

The function of the present invention is to replace the nucleus 14 of adisc 12 with a prosthesis 46.

In replacing the lumbar intervertebral disc 12, a tube 31 is insertedlaterally to a location abutting the injured disc 12. The tube 31 isinserted in such manner as to move out of the way the adjacent nerves23. Tube 31 has a longitudinal hole 32 in its wall to receive a pin 33having an outwardly curved sharpened point 34 which is imbedded in theadjacent vertebrae to secure the anterior of tube 31 in the desiredlocation. To prevent excessive penetration of pin 33, a stop 56 slipsover the pin 33 on the exterior of tube 31 and is held in place by setscrew 57 so that point 34 projects from tube 31 the desired amount.Optionally, an instrument (not shown) is inserted through the bore intotube 31 to spread the adjacent vertebrae ll apart by tilting same asshown in FIG. 3, whereupon a second pin 33a is installed in a hole 32adiametrically opposite hole 32 and a second pin 330 having point 34a isdriven into the vertebrae 11a holding the vertebrae in spread apartcondition and affording greater space for the surgical treatmenthereinafter described. Preferably, tube 31 is transparent or has atransparent window or is formed with a slot so that a cystoscope (notshown) may be inserted in the bore of tube 31 and the location of thetube relative to disc 12 and also relative to the nerve and adjacentanatomy may be checked.

The annulus 13 adjacent tube 31 is penetrated and a forceps 36 havingpincers 37 at the anterior thereof is used to remove the remainingnucleus of disc 12. Thus a void 27 is created inside the annulusfibrosis of disc 12 into which the prosthesis 46 is subsequentlyinstalled.

A second forceps 38 having fitted ends 39 is used to insert socketmembers 41. Each socket member 41 has a peripheral flange 42 and ahollow pointed prong. Preferably the socket forming members 41 areinserted serially, the flange 42 being captured in one end 39 andinserted through the tube 31 into the void 27 in the disc 12. The prong43 is imbedded through the cartilage l9 and bony end plate into thesurface 17 of the adjacent vertebrae ll. Thereupon a second socketmember 41 is installed in the opposite vertebrae in the same manner.Socket members 4] may be of ceramic, plastic, or autogenous bonematerial and are preferably opaque in radiology.

Prosthesis 46 is a hollow, bladder-like member having in expanded shapethe appearance of the natural nucleus 14 of a natural disc 12. It has awall approximately 0.040 inches in thickness and for a typical lumbardisc has a width on its major axis of 1.375 inches and on its minor axisof 0.800 inches. Projecting at an angle of approximately 45 relative tothe major axis of the prosthesis is a stem 47 of 0. l 25 inches insidediameter tubing. Preferably a valve 48 is similar to a ball check valveis installed in the stem 47. On the top and bottom surfaces ofprosthesis 46 are studs 49 preferably bulbous and integrally formed withthe bladder of the prosthesis. The studs 49 are dimensioned to fit intothe hollow prongs 43 of the socket members 41. The material ofconstruction of prosthesis 46 preferably has certain characteristics. Ithas properties of holding fluid or water under pressure substantiallyduplicating the normal disc. It has electrical conductivity conformingto the normal disc. The fluid or plastic within the disc preferably hassimilar conductivity and is opaque in ra diology.

As viewed in H6. 6, the prosthesis 46 is installed through tube 31flattened and preferably folded. The flattened condition may be bestattained by evacuation of the bladder. After the prosthesis is in placein the void 27, the studs 49 are located in alignment with the hollowprongs 43, a probe being used for this purpose and the location beingchecked by television fluoroscopic radiography. To facilitate thisoperation. members 43 and 49 are preferably radio opaque. Thereupon.fluid is pumped through the stem 47 past the check valve 48 to expandthe prosthesis to the condition shown in FIG. 5, filling the void 27 andfunctioning as a healthy nucleus 14 would function in a natural disc 12.The stem 47 may be left in place for some time, preferably terminatingnear the skin so that from time to time the amount of fluid may beincreased or reduced until the desired pressure is determined by trialand error. Subsequently, the stem 47 may be cut off ad jacent the valve48. Various fluids may be used to expand the prosthesis, but preferablyone which offers a radio opague feature to assist in checking positionby radiography.

Directing attention to FlGS. 8 and 9. use of prosthe ses 46b in cervicalvertebrae is shown. The prosthesis is the same in structure andfunction, but of reduced size from that previously described.

However, installation is somewhat simplified. lncision is made frontallyto one side of windpipe 53, the adjacent artery 51 and vein 52 beingretracted. Thus use of tube 31 may not be advantageous in the neck.

The cervical vertebrae and prosthesis are marked with reference numeralsas in the preceding modification. followed by subscript b.

What is claimed is;

l. A prosthesis for the nucleus pulposis of an intervertebral disccomprising a bladder-like member having a stern for insertion of liquidor plastic into said member, said member shaped to simulate said nucleuspulposis of a human disc and to fit within the annulus fibrosis of saiddisc and at least one stud on an exterior face of said member shaped toengage a socket forming member on one end of said disc formed forinstallation in the vertebrae along or below said disc.

2. A prosthesis according to claim 1 in which said bladder-like memberis a thin-walled plastic member capable of being rolled up preliminaryto installation formed of a material having approximately the electricalconductivity of a natural disc, and capable of holding fluid or waterunder pressure substantially duplicating the correspondingcharacteristics of a natural disc nucleus pulposis.

3. A prosthesis according to claim 2 in which said stud is radio opaque.

4. A prosthesis according to claim 1 which further comprises a valve insaid stem.

5. A prosthesis according to claim 1 which further comprises materialinserted through said stern substantially filling said bladder-likemember, said material being radio opaque, said material being fluid orplastic.

6. A prosthesis according to claim 5 in which said material is radioopaque.

7. A prosthesis according to claim 1 which further comprises at leastone socket forming member having a flange and shaped with a point toimbed said socketforming member into a vertebrae above or below saidflange, said socket-forming member formed with a socket complementary tosaid stud.

8. A prosthesis according to claim 7 in which said socket-forming memberis radio opaque.

9. In combinaton with a prosthesis of claim 1, a tube for surgicallylocating said prosthesis. said tube being transparent in at least aportion of its distal end for checking location of said tube with acystoscope inserted into said tube, said tube having locating meansoperable from its proximal end to drive at least one pin at its distalend into a vertebrae to locate said tube fixed relative to a disc inwhich said prosthesis is to be installed.

10. The combination of claim 9 which further comprises a socket-formingmember having a flange, a point and a socket complementary to said stud,and a forceps dimensioned to fit inside said tube and having one endformed to hold said flange for insertion of said point into an adjacentvertebrae by operation of said forceps.

11. The combination of claim 9 in which the wall of said tube is formedwith a longitudinal hole and said locating means comprises a pinreciprocable in said hole and having a point in its distal end.

12. The combination of claim 11 in which the wall of said tube is formedwith a second longitudinal hole diametrically opposite saidfirst-mentioned hole and which further comprises a second pin in saidsecond hole to locate said tube fixed relative to said first-mentionedvertebrae and a second vertebrae on the side of said disc opposite saidfirst-mentioned vertebrae.

13. The combination of claim 9 which further comprises a stop and meansadjustably securing said stop on said pin outside said tube to limitinward projection of said pin into said tube.

1. A prosthesis for the nucleus pulposis of an intervertebral disccomprising a bladder-like member having a stem for insertion of liquidor plastic into said member, said member shaped to simulate said nucleuspulposis of a human disc and to fit within the annulus fibrosis of saiddisc and at least one stud on an exterior face of said member shaped toengage a socket forming member on one end of said disc formed forinstallation in the vertebrae along or below said disc.
 2. A prosthesisaccording to claim 1 in which said bladder-like member is a thin-walledplastic member capable of being rolled up preliminary to installationformed of a material having approximately the electrical conductivity ofa natural disc, and capable of holding fluid or water under pressuresubstantially duplicating the corresponding characteristics of a naturaldisc nucleus pulposis.
 3. A prosthesis according to claim 2 in whichsaid stud is radio opaque.
 4. A prosthesis according to claim 1 whichfurther comprises a valve in said stem.
 5. A prosthesis according toclaim 1 which further comprises material inserted through said stemsubstantially filling said bladder-like member, said material beingradio opaque, said material being fluid or plastic.
 6. A prosthesisaccording to claim 5 in which said material is radio opaque.
 7. Aprosthesis according to claim 1 which further comprises at least onesocket forming member having a flange and shaped with a point to imbedsaid socket-forming member into a vertebrae above or below said flange,said socket-forming member formed with a socket complementary to saidstud.
 8. A prosthesis according to claim 7 in which said socket-formingmember is radio opaque.
 9. In combinaton with a prosthesis of claim 1, atube for surgically locating said prosthesis, said tube beingtransparent in at least a portion of its distal end for checkinglocation of said tube with a cystoscope inserted into said tube, saidtube having locating means operable from its proximal end to drive atleast one pin at its distal end into a vertebrae to locate said tubefixed relative to a disc in which said prosthesis is to be installed.10. The combination of claim 9 which further comprises a socket-formingmember having a flange, a point and a socket complementary to said stud,and a forceps dimensioned to fit inside said tube and having one endformed to hold said flange for insertion of said point into an adjacentvertebrae by operation of said forceps.
 11. The combination of claim 9in which the wall of said tube is formed with a longitudinal hole andsaid locating means comprises a pin reciprocable in said hole and havinga point in its distal end.
 12. The combination of claim 11 in which thewall of said tube is formed with a second longitudinal holediametrically opposite said first-mentioned hole and which furthercomprises a second pin in said second hole to locate said tube fixedrelative to said first-mentioned vertebrae and a second vertebrae on theside of said disc opposite said first-mentioned vertebrae.
 13. Thecombination of claim 9 which further comprises a stop and meansadjustably securing said stop on said pin outside said tube to limitinward projection of said pin into said tube.